Silicondust Prime Discovery

[EnterNoEscape]

I actually bought a Prime for myself because I wanted to see what it can do more than the InfiniTV. I'm also developing a DCT network encoder (in Java) for it and the InfiniTV. I discovered something I'm not sure most people are aware of. If you set the PID filter to not filter at all, you get all of the programs (essentially channels) on that frequency. That can be anywhere from 2 to 6+ programs being recorded at the same time. I know people take advantage of this on DVB tuners, I tried this many different ways on the InfiniTV and never actually got more than that program I had selected. The PMT still contained the other programs, but the packets associated with the other PID's would never show up. I'm very excited to think that I should be able to harness this to record most of the locals with one tuner. I hope this isn't an accident on Silicondust's part and they fix it.

I already know filtering out PID's in a TS stream is trivial and I already wrote code to parse the PMT (needed to know what program uses what PID's), so I can't wait to implement this kind of tuning device. I never fully understood if the scheduler actually knows how to handle a device set up like this. Does anyone have any insights on this kind of tuner?

Joe

[Fonceur]

That was also the case for their original recorder and some of the smaller PVR software were making use of it back then...

I know that it took some time for Snapstream to actually start filtering out the other channels.

[Fuzzy]

Originally Posted by EnterNoEscape

I actually bought a Prime for myself because I wanted to see what it can do more than the InfiniTV. I'm also developing a DCT network encoder (in Java) for it and the InfiniTV. I discovered something I'm not sure most people are aware of. If you set the PID filter to not filter at all, you get all of the programs (essentially channels) on that frequency. That can be anywhere from 2 to 6+ programs being recorded at the same time. I know people take advantage of this on DVB tuners, I tried this many different ways on the InfiniTV and never actually got more than that program I had selected. The PMT still contained the other programs, but the packets associated with the other PID's would never show up. I'm very excited to think that I should be able to harness this to record most of the locals with one tuner. I hope this isn't an accident on Silicondust's part and they fix it.

I already know filtering out PID's in a TS stream is trivial and I already wrote code to parse the PMT (needed to know what program uses what PID's), so I can't wait to implement this kind of tuning device. I never fully understood if the scheduler actually knows how to handle a device set up like this. Does anyone have any insights on this kind of tuner?

Joe

The SageTV Scheduler has no concept of being able to use a single input for multiple recordings. The only way to get this to work with sage as it stands is to have the network encoder virtualize the tuners, so that your 3 tuner Prime could show up as 6 or so tuners in sage. This would allow sage to schedule more at a time, but at the same time, would be a problem if 4 of those end up being on different frequencies.

the 'right' fix would be to rewrite the scheduler to acknowledge this capability, but that is no small undertaking, and seriously tampers with the single most important part of sagetv. Aside from the scheduling issues, Sage would need to know what channels are ON what frequencies, which it currently does not, as that mapping is all done in either the CableCard or the Tuning Adapter, and can change on a whim (can even change between tunings, if using a tuning adapter on SDV).

In short, don't expect much from looking down this path.

[Monedeath]

Originally Posted by Fuzzy

the 'right' fix would be to rewrite the scheduler to acknowledge this capability, but that is no small undertaking, and seriously tampers with the single most important part of sagetv. Aside from the scheduling issues, Sage would need to know what channels are ON what frequencies, which it currently does not, as that mapping is all done in either the CableCard or the Tuning Adapter, and can change on a whim (can even change between tunings, if using a tuning adapter on SDV).

I could see it getting done conceptually, but yeah, the resulting code might bear a resemblance to something only a mind like H.P. Lovecraft would love.

You would need to implement a way for Sage to regularly monitor the frequency <-> channel mapping on certain (flagged?) device types(It is unlikely that a service provider is going to change them very frequently(more the once a day, for arguments sake) on non-SDV systems, but there still is a giant question mark as to when they'd implement such a change. For OTA providers however, it isn't very likely to see a channel lineup change unless they're taking a given sub-channel off-air or otherwise repurposing it for something else)

Possibly have it make queries to the relevant scheduled recording devices ___ amount of time prior to either scheduled recording start time, or when the tuner/device/input source is scheduled to become busy?

Which adds more complexity as you'd need to make sure that Sage knows that tuner __ is on the same input source as tuner _. Particularly where network tuners are involved. "Easy fix" is to relegate such things as being "advanced configuration options" and require manual configuration by users wanting to use it.

Which isn't to mention the confusion that can be had regarding people differentiating between tuners/devices/input sources or whatever you want to call it(content provider?).

Some devices use different physical inputs for different tuners/content sources(ATSC/NTSC/SVHS/Component/Composite/Etc), so they would have different physical input sources per tuner on a single device.

While in the more recent tuners in particular, it is now common to see multiple tuners tied to one physical input source. For those devices, what one tuner sees, the other tuners have a very high chance of seeing the exact same thing.

But then it also is not uncommon to see multiple devices sharing a common input(content) source, even if they don't share a (final) physical connection. In which case you can end up with multiple devices having a high chance of seeing virtually the exact same thing(after accounting for slight differences in cabling, tuner device construction, quality of the physical connection, etc), so the only real difference they should see between each other is signal quality, which I don't think SageTV really tracks currently(but could be used to verify sub-channel groupings all the same).

Of course, going back to the OTA crowd, you can also end up with multiple types of content providers using the same type of input. One antenna picking up OTA content from the NW, and another antenna doing so towards the South, plus who knows what else.

So yeah, a whole lot of new things to try to keep track of and implement before getting very far into the scheduler.

IF someone was going to try to implement something like this, I'd tend to say a good "milestone 1" would be trying to get it implemented for OTA tuners first. They're likely to be the most stable in terms of channel lineups not shifting around on anything approaching a frequent basis(likely going months, if not years between changes). Then possibly venturing into the realm of QAM and Cable Cards for Milestone 2, with the handling for SDV as the final step.

[Fuzzy]

It's not a matter of sage polling the tuner for the channel mappings - they simply aren't available to the server. The prime doesn't make the channel maps (either cablecard OR tuning adapter) available, because in most cases, they are not needed. Frankly, the cost of a second prime is just not that much.

OTA would work easily enough to do this, but this thread was talking about the Prime.

[EnterNoEscape]

I must be in the minority. I have not seen any of my channel frequencies shift around on me other than when FiOS removed a channel, or moved it to another channel which you would expect could likely put it in a different frequency. The only way I have come up with to get the mappings from the prime is to just tune a channel and check what frequency and program it tuned in.

Another thought is to just fix the tuner on a frequency and tell SageTV those are the only channels you can tune into while creating network encoders equal to the number of available channels. It's a bit lame, but it could work out for you if those just happen to be channels you record from around the same hours all of the time.

If you really wanted to go nuts, you could create a tuner for each channel over several frequencies and simply make the tuners related to currently unreachable frequencies unavailable. It could even be a little predictive by checking the recording schedule and making adjustments accordingly. Of course, that would cause the scheduler to kick off several times or even get you into a scheduling loop. Obviously it's a ridiculous idea, but in theory it's possible.

[Monedeath]

I used QAM to tune into locals for more than a few years, it was reasonably stable that way for years, with only a rare technical issue that would cause them to flip channels around before flipping them back.....

Then they transitioned to a full digital lineup. The QAM channel lineups were doing good to be stable for more than a few weeks before needing rescaned and configured, after the third month(we held out that long because we expected there to be a lot of shifting around happening during the transition), we resolved it by shifting those tuners to OTA instead. The only tuners that now remain on the wire from Cable One is the CableCard, which gets its channel tuning/mapping info from them.

[Fuzzy]

Originally Posted by EnterNoEscape

I must be in the minority. I have not seen any of my channel frequencies shift around on me other than when FiOS removed a channel, or moved it to another channel which you would expect could likely put it in a different frequency. The only way I have come up with to get the mappings from the prime is to just tune a channel and check what frequency and program it tuned in.

Another thought is to just fix the tuner on a frequency and tell SageTV those are the only channels you can tune into while creating network encoders equal to the number of available channels. It's a bit lame, but it could work out for you if those just happen to be channels you record from around the same hours all of the time.

If you really wanted to go nuts, you could create a tuner for each channel over several frequencies and simply make the tuners related to currently unreachable frequencies unavailable. It could even be a little predictive by checking the recording schedule and making adjustments accordingly. Of course, that would cause the scheduler to kick off several times or even get you into a scheduling loop. Obviously it's a ridiculous idea, but in theory it's possible.

You must not have SDV in your market. With SDV, what channels are provided to you on which frequency can change every time it is tuned. The way SDV works, is when someone in your neighborhood tunes to a given channel, it find an empty slot in what it's currently broadcasting to that neighborhood, and puts that channel on that part of that frequency. It will remain there as long as someone in the neighborhood is tuning that channel. When no-one is, however, it will be removed, and that channel simply will not be broadcast to that neighborhood. This allows them to only devote enough frequencies to the tv services as are actually being watched, and use more of the spectrum for internet and phone services.

[EnterNoEscape]

I had not considered the dynamics of that kind of situation. I understand how SDV works, and have been thankful that I don't need one of those USB devices to accompany my tuner. I didn't think that many markets used it. I think I will just relegate this to just being something fun to play around with since it clearly will not be a benefit to most people. Do you actually run into situations whereby you can't tune into a channel because all of the bandwidth allocated to channels is being used? Or does it just negatively effect overall internet traffic throughput?

[Monedeath]

Originally Posted by EnterNoEscape

I had not considered the dynamics of that kind of situation. I understand how SDV works, and have been thankful that I don't need one of those USB devices to accompany my tuner. I didn't think that many markets used it. I think I will just relegate this to just being something fun to play around with since it clearly will not be a benefit to most people. Do you actually run into situations whereby you can't tune into a channel because all of the bandwidth allocated to channels is being used? Or does it just negatively effect overall internet traffic throughput?

I'd imagine TV Service has the highest priority, so yes, a SDV system would likely just "open a new channel" to handle to SDV user, and the people using the internet on that particular service loop will lose a corresponding amount of bandspace corresponding to the type of content being provided on that "channel."

[Fuzzy]

Originally Posted by EnterNoEscape

I had not considered the dynamics of that kind of situation. I understand how SDV works, and have been thankful that I don't need one of those USB devices to accompany my tuner. I didn't think that many markets used it. I think I will just relegate this to just being something fun to play around with since it clearly will not be a benefit to most people. Do you actually run into situations whereby you can't tune into a channel because all of the bandwidth allocated to channels is being used? Or does it just negatively effect overall internet traffic throughput?

Spectrum is not dynamically moved between internet and tv services as needed, it just takes proper planning and allocation to ensure the channels are available. MOST channels on a cable lineup are not viewed all that often, and many channels are viewed by nearly every household. If a station is already being broadcast to a given neighborhood, then any new tuning requests simply use that same broadcast. Things like Prime-time tv, and such, make SDV a non-impact for users, in fact, most cable users wouldn't even know it's there. Not every channels is an SDV channel, either. The most popular ones, which would end up being in request most the time anyway, are already broadcast on fixed channels. SDV is mostly used for a bulk of the 'extra' channels. (again, this is all at the discretion of that individual head end configuration).